JP2007214253A - Extreme ultra-violet light source device and method for protecting light-condensing optical means in it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit the damage of a reflecting film for a light-condensing optical means for condensing an EUV light, and to achieve the lengthening of the lifetime of the light-condensing optical means even in the case of a continuous operation for a prolonged term. <P>SOLUTION: High-voltage pulses are applied between first and second main discharging electrodes 2a and 2b, a high-density high-temperature plasma is formed, and the EUV light having a wavelength of 13.5 nm is radiated. The EUV light is condensed by an EUV-light condensing mirror 3 and extracted to the outside. A protective-film material feeder 20 composed of a protective-film material 21 and a heating apparatus 22 is fitted to at least either of the inside of a second vessel 1b in the vicinity of the EUV-light condensing mirror 3 or the inside of a first vessel 1a. Si, Sr or the like as a solid form is heated and vaporized, and a protective film is formed on the surface of the EUV-light condensing mirror 3. Accordingly, a debris does not reach the reflecting film formed on the surface of the EUV-light condensing mirror 3, and a reflectivity to the EUV light can be maintained. The protective film may also be formed previously on the surface of the reflecting film for the EUV-light condensing mirror 3 by a sputtering or the like. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an extreme ultraviolet light source device that emits extreme ultraviolet light and a method for protecting condensing optical means in the extreme ultraviolet light source device, and in particular, a protective film is applied to the condensing optical means that collects extreme ultraviolet light. The present invention relates to an extreme ultraviolet light source device and a method for protecting the condensing optical means, which are intended to extend the life of the condensing optical means.

With the miniaturization and high integration of semiconductor integrated circuits, improvement in resolving power is demanded in the projection exposure apparatus for production. In order to meet the demand, the wavelength of the exposure light source has been shortened. As a next-generation semiconductor exposure light source following the excimer laser apparatus, EUV (Extreme Ultra Violet: extreme ultraviolet) having a wavelength of 13 to 14 nm, particularly a wavelength of 13.5 nm. ) Extreme ultraviolet light source devices that emit light (hereinafter also referred to as EUV light source devices) have been developed.
Several methods for generating EUV light in an EUV light source device are known. One of them is to generate a high-density and high-temperature plasma by heating and excitation of EUV radiation species, and to generate EUV light emitted from this plasma. There is a way to take it out.
The EUV light source apparatus adopting such a method uses an LPP (Laser Produced Plasma) type EUV light source apparatus and a DPP (Discharge Produced Plasma) type EUV light source apparatus by a high-density and high-temperature plasma generation system. (See Non-Patent Document 1, for example).

The LPP EUV light source device uses EUV radiation from high-density and high-temperature plasma generated by irradiating a target such as a solid, liquid, or gas with a pulse laser.
On the other hand, the DPP EUV light source device uses EUV radiation from high-density and high-temperature plasma generated by current driving. As described in Non-Patent Document 1, there are a Z-pinch method, a capillary discharge method, a plasma focus method, a hollow cathode trigger Z-pinch method, etc. as discharge methods in the DPP EUV light source.
Compared with the LPP EUV light source, the DPP EUV light source has advantages such as downsizing of the light source device and low power consumption of the light source system, and high expectations for practical use.
In both types of EUV light source devices described above, as a radioactive species that emits EUV light having a wavelength of 13.5 nm, that is, as a raw material for high-density and high-temperature plasma, currently about 10-valent Xe (xenon) ions and Sn (tin) ions are present. It is considered promising.

FIG. 23 shows a schematic configuration example of a DPP EUV light source device.
As shown in FIG. 23, the DPP EUV light source device has a chamber 1 that is a discharge vessel. In the chamber 1, for example, a ring-shaped first main discharge electrode 2a (cathode) and a second main discharge electrode 2b (anode) are arranged with a ring-shaped insulating material 2c interposed therebetween. The chamber 1 includes a first container 1a arranged on the first main discharge electrode 2a side made of a conductive material and a second container arranged on the second main discharge electrode 2b side made of the same conductive material. Container 1b. The first container 1a and the second container 1b are separated and insulated by the insulating material 2c.
The ring-shaped first main discharge electrode 2a, the second main discharge electrode 2b, and the insulating material 2c are arranged so that the respective through holes are positioned substantially on the same axis, thereby forming a communication hole.
The first main discharge electrode 2a and the second main discharge electrode 2b are made of a refractory metal such as tungsten, molybdenum, or tantalum. The insulating material 2c is made of, for example, silicon nitride, aluminum nitride, diamond, or the like.

A raw material containing EUV radioactive species is supplied into the chamber 1 from a raw material supply unit 9 connected to a raw material inlet 10 provided on the first container 1 a side of the chamber 1. Examples of the raw material include SnH ₄ gas and Xe gas.
A gas exhaust unit 12 for adjusting the pressure in the chamber 1 and exhausting the chamber based on the measurement value of the pressure monitor 7 for monitoring the pressure in the chamber is provided on the second container 1b side of the chamber 1. Connected to the outlet 5.
Further, in the second container 1b of the chamber 1, there is provided an EUV collector mirror 3 which is a grazing incidence type condensing optical means for condensing EUV light. The EUV collector mirror 3 includes, for example, a plurality of spheroids having different diameters or mirrors having a rotating parabolic shape. These mirrors are arranged on the same axis so as to overlap the rotation center axis so that the focal positions substantially coincide with each other. For example, on the reflecting surface side of the base material having a smooth surface made of nickel (Ni) or the like, ruthenium ( By densely coating a metal film such as Ru), molybdenum (Mo), and rhodium (Rh), EUV light having an oblique incident angle of 0 ° to 25 ° can be favorably reflected.

In such a DPP-type light source device, when a pulse power is supplied from the high voltage pulse generator 14 between the first and second main discharge electrodes 2a and 2b, creeping discharge is generated on the surface of the insulating material 2c. The first and second main discharge electrodes 2a and 2b are substantially short-circuited and a large pulse current flows.
At this time, plasma is formed in or near the communication hole formed by the ring-shaped first main discharge electrode 2a, second main discharge electrode 2b, and insulating material 2c arranged substantially coaxially. Thereafter, a high-density and high-temperature plasma region is formed at a substantially central portion of the plasma by Joule heating by the pinch effect, and EUV light having a wavelength of 13.5 nm is emitted from the high-density and high-temperature plasma region.
The EUV light having a wavelength of 13.5 nm emitted from the high-density and high-temperature plasma region is collected by the above-described EUV collector mirror 3 and taken out from the EUV light extraction unit 6 provided in the second container 1b.
The EUV light extraction unit 6 is connected to an EUV light incident unit provided in an exposure machine casing (not shown) of the exposure machine. That is, the EUV light collected by the EUV collector mirror 3 enters the exposure device via the EUV light extraction unit 6 and the EUV incident unit (not shown).

The DPP light source device may be provided with a preionization means for preionizing a raw material containing EUV radiation species supplied into the chamber 1 when a discharge is generated in the chamber 1.
When generating EUV light, the pressure in the chamber 1 is adjusted to 1 to 20 Pa, for example. Under such a low pressure, it is difficult for electric discharge to occur depending on the electrode structure, and as a result, the output of EUV light may become unstable. In order to generate a stable discharge in a situation where the discharge is difficult to occur, it is desirable to perform preionization.
In the case shown in FIG. 23, a preionization unit 8 is provided in the first container 1a.
The preionization unit 8 includes a first preionization member 8a and a second preionization member 8c made of a cylindrical conductive material, and a first preionization member 8a and a second preionization member 8c made of a cylindrical insulating material. It consists of a preionization insulating material 8b disposed so as to be sandwiched between the preionization member 8c.
The preliminary ionization unit 8 is disposed above and coaxially with the high-density and high-temperature plasma generation unit 11 so as to effectively pre-ionize the raw material containing EUV radiation species existing in the high-density and high-temperature plasma generation unit 11. Yes.
The conductive second preionization member 8 c is connected to one terminal of the preionization power supply unit 13. Note that the other terminal of the preionization power supply unit 13 is connected to the conductive first preionization member 8a via the conductive first container 1a.

When a voltage pulse is applied from the preionization power supply unit 13 between the second preionization member 8c and the first container 1a of the chamber 1, as shown in FIG. 23, the surface of the preionization insulating material 8b is applied. A creeping discharge is generated to promote ionization of the raw material containing EUV radiation species introduced into the chamber 1.
Here, the cylindrical first preliminary ionization member 8a, the preliminary ionization insulating material 8b, and the second preliminary ionization member 8c that are coaxially arranged also have a raw material supply path for supplying a raw material containing EUV radiation species. Also serves as.
An example in which a preliminary ionization unit is combined with a DPP EUV light source device is disclosed in Patent Document 1, for example.

High-density and high-temperature plasma region (in the configuration example shown in FIG. 23, communication holes or communication formed by the ring-shaped first main discharge electrode 2a, second main discharge electrode 2b, and insulating material 2c arranged substantially coaxially. Between the vicinity of the hole) and the EUV collector mirror 3, the metal (for example, the discharge electrode) in contact with the high-density and high-temperature plasma is sputtered by the plasma to generate debris such as metal powder, or radiation species such as Sn. A debris trap 4 for capturing debris and the like and allowing only EUV light to pass through is installed. As described in Patent Document 2, for example, the debris trap 4 is composed of a plurality of plates installed in the radial direction of the high-density and high-temperature plasma generation region.
The DPP EUV light source apparatus shown in FIG. The control unit 30 controls the high voltage pulse generation unit 14, the preionization power supply unit 13, the raw material supply unit 9, and the gas exhaust unit 12 based on an EUV emission command from the exposure machine control unit 31.

By the way, as described above, the DPP type EUV light source device uses EUV radiation from high-density and high-temperature plasma generated by current driving by discharge, and the heating / excitation means for EUV radiation type is a pair of discharges. This is a large current due to the discharge generated between the electrodes. Therefore, the discharge electrode receives a large thermal load accompanying the discharge and also receives a thermal load from the high-density high-temperature plasma.
Such a thermal load gradually wears the discharge electrode. In order to cope with such a problem, Non-Patent Document 2 discloses that in a method of supplying a raw material for high-density and high-temperature plasma in a liquid or solid state, the electrode is rotated to move the raw material for high-density and high-temperature plasma to the discharge part. An apparatus for moving is proposed.
JP 2003-218025 A JP-T-2002-504746 “Current Status and Future Prospects of Research on EUV (Extreme Ultraviolet) Light Sources for Lithography” J. Plasma Fusion Res. Vol. 79. No. 3, P219-260, March 2003 “EUV sources using Xe and Sn discharge plasmas” J.Phys. D: Appl.Phys.37 (2004) 3254-3265

The debris trap 4 described above does not necessarily supplement all the debris. In particular, most of the debris caused by EUV radiation species such as Xe is lighter in weight than the debris such as metal powder, and is less likely to travel straight, so that it easily passes through the debris trap 4.
That is, debris such as metal powder emitted from the vicinity of the light source travels in a constant direction with constant velocity motion after generation. Therefore, the debris trap 4 configured correspondingly works effectively for capturing debris such as metal powder. On the other hand, debris caused by radioactive species such as Xe is Xe in an atomic gas state, and its process is complicated, so that it often passes through the debris trap 4.
Here, debris caused by EUV radiation species such as Xe that has passed through the debris trap 4 is generally a high-speed ion or atom having high kinetic energy.
As described above, the plasma generated between the first main discharge electrode 2a and the second main discharge electrode 2b is pinched in a radial direction by a magnetic field generated by a pulsed large current flowing between the two electrodes. Receive the effect. Due to the Joule heating due to the pinch effect, a pinch plasma region, which is a high-density high-temperature plasma, is generated at substantially the center of the plasma.
The generated pinch plasma is electrically in a substantially neutral state, and is composed of neutral atoms, ions, and electrons.

Thereafter, the self-magnetic field of the discharge current attenuates as the discharge current value decreases. Therefore, the force for contracting the plasma is reduced, and it is gradually difficult to maintain the pinch plasma, and the pinch plasma is adiabatically expanded in the direction of the solid angle 4π. That is, the pinch plasma collapses, and ions and neutral atoms are scattered at high speed and debris in all directions. For example, when the rare gas is Xe, the speed of Xe ions scattered at a high speed is several thousand m / s or more.
When moving in the gas, high-speed ions collide with neutral atoms and exchange electric charges, or collide with electrons and recombine to become neutral atoms as the distance from the plasma increases. When these high-speed ions or atoms collide with the reflecting film of the condensing optical means (EUV condensing mirror 3) that collects EUV light, the high-speed ions or neutral atoms collide with the reflecting film atoms to cause high-speed The kinetic energy of ions or neutral atoms is given to the reflecting film atoms, the reflecting film atoms jump out into the gas, and as a result, they are peeled off from the EUV collector mirror 3. Alternatively, high-speed ions or neutral atoms are injected into the reflective film of the EUV collector mirror 3.
That is, conventionally, debris caused by EUV radiation species that are high-speed ions or neutral atoms collide with the EUV collector mirror 3, and as a result, on the surface of the EUV collector mirror that has high reflectivity for EUV light. There has been a problem that the reflective film applied is damaged and the reflectance of the EUV collector mirror 3 with respect to the EUV light is lowered.

As a measure for dealing with such a problem, it is conceivable to introduce a gas into the above-described ion or neutral atom scattering path. That is, by increasing the collision frequency between the introduced gas atoms or molecules in the scattering path and high-speed ions or neutral atoms that are debris caused by EUV radiation species, a part of the kinetic energy of the high-speed ions or neutral atoms is increased. Are transferred to the introduced gas atoms or molecules in the scattering path. Thereby, the kinetic energy which the debris resulting from the above-mentioned EUV radiation species has decreases, and the scattering speed of the debris is considered to decrease.
That is, by colliding the gas introduced into the scattering path with the debris caused by the EUV radiation species, the collision energy when the debris collides with the reflective film of the EUV collector mirror 3 is reduced. As a result, the EUV It is considered that the damage that the reflective film of the condenser mirror 3 suffers from debris can be reduced.

However, in this case, it is necessary to consider the influence of light absorption of EUV light by the introduced gas (for example, He gas). In order to extract EUV light efficiently, it is necessary to keep the light absorption of EUV light in the optical path from the high-density and high-temperature plasma generation unit 11 to the EUV light extraction unit 6 as low as possible. Therefore, it is necessary to maintain a vacuum degree of 100 Pa or less in the optical path.
Therefore, the pressure of the gas introduced into the above-described scattering path cannot be set larger than 100 Pa. In this case, it is difficult to sufficiently decelerate debris caused by EUV radiation species. That is, when the gas is introduced into the scattering path at a pressure of 100 Pa or less, the occurrence of damage to the reflective film of the EUV collector mirror 3 is suppressed as compared with the case where the gas is not introduced into the scattering path. However, it is difficult to sufficiently suppress the occurrence of damage to the reflective film of the EUV collector mirror 3, and as a light source for an exposure apparatus using EUV light having a long operation time, it has a short life and is not practical.
The present invention has been made in view of the above circumstances, and its problem is that a reflective film of a condensing optical means that condenses EUV light even when continuously operating as a light source for an exposure apparatus for a long period of time. The extreme ultraviolet light source device that can suppress the damage of the light and realize the long life of the condensing optical means, and a method for protecting the condensing optical means in the extreme ultraviolet light source device.

The present invention suppresses damage to the reflective film by applying a protective film having a high transmittance to EUV light on the reflective film surface of the condensing optical means.
That is, the said subject is solved as follows.
(1) Raw material supply means for supplying a raw material containing an extreme ultraviolet light emitting species and / or a compound of an extreme ultraviolet light emitting species, and heating / excitation for heating and exciting the supplied material to generate high-density high-temperature plasma. And a grazing incidence type condensing optical means for converging extreme ultraviolet light emitted from the high-density high-temperature plasma, an Si film or an Sr film on the surface of the condensing optical means Apply.
That is, a reflective film formed by densely coating a metal film such as ruthenium (Ru), molybdenum (Mo), and rhodium (Rh) on the reflective surface side of a base material having a smooth surface made of nickel (Ni) or the like. In the oblique incident type condensing optical means, a protective film is further provided on the surface of the reflective film. The protective film is formed by, for example, sputtering.
When debris (high-speed ions or neutral atoms) caused by EUV radiation species collides with the condensing optical means configured in this way, the debris may gradually scrape the protective film due to elastic collision with the protective film. Or injected into the protective film. However, while the protective film is present, debris does not reach the reflective film provided on the surface of the condensing optical means having a high reflectivity with respect to EUV light. The reflectivity of the optical optical means for EUV light is also maintained.
For example, silicon (Si) or strontium (Sr) is preferably used as the protective film.
In particular, when the gas is introduced into the debris scattering path at a pressure of 100 Pa or less, it is possible to further extend the life of the EUV collector mirror.
The present invention is applied to a grazing incidence type condensing optical means whose reflecting film is a metal film, and in a total reflection type EUV condensing mirror whose reflecting film is a multilayer film of Mo and Si. For example, if a separate Si film is applied as a protective film, the EUV reflectance in a reflective film that is a multilayer film of Mo and Si is lowered, which is not appropriate.
(2) As described above, the protective film is applied to the reflective film surface of the condensing optical means, so that debris does not reach the reflective film. For this reason, the reflective film is not damaged, and the reflectance of the EUV collector mirror with respect to EUV light is maintained.
However, the above-mentioned debris is gradually shaved or injected into the protective film due to elastic collision with the protective film, and the protective film gradually becomes thinner while being used for a long time.
Therefore, in the extreme ultraviolet light source device having the above configuration, a protective film material supply means is provided, and a protective film material such as Si or Sr is supplied to the condensing optical means. As a result, the life of the EUV collector mirror can be further extended.
(3) The protective film material supply means of (2) above comprises a protective film material and a heating means for heating and evaporating the protective film material.
(4) The heating means of (3) above is the heating / excitation means. Alternatively, when the extreme ultraviolet light source device is provided with a preionization unit for preionizing the raw material, the heating unit is used as the preionization unit. Then, the protective film material is evaporated by thermal radiation of the heating / excitation means and / or the preliminary ionization means.
(5) In the above (3) and (4), the protective film material supply means is provided with a material supply means for supplying the protective film material.
(6) In the above (4) and (5), the extreme ultraviolet light source device is further provided with means for adjusting the gas pressure of the atmosphere of the condensing optical means.
(7) In the above (2), the protective film material supply means is used as a protective film material gas supply means, and a gaseous protective film material is supplied.
(8) In the above (2) to (7), the protective film material supply means is provided on the light incident side of the condensing optical means.
(9) In the method for protecting the condensing optical means of the extreme ultraviolet light source device having the configuration of (1) above, during the operation of the extreme ultraviolet light source apparatus, the condensing optical means is moved from the protective film material supplying means to the Si Alternatively, Sr is supplied, and a Si film or Sr film is formed as a protective film on the surface of the condensing optical means to protect the condensing optical means.
(10) In (9), the thickness of the protective film of the condensing optical means is monitored, and the protective film material is supplied from the protective film material supply means so that the thickness of the protective film becomes a predetermined value. Control the amount.
(11) In the above (9), the film thickness of the protective film of the light collecting optical means is monitored, and the pressure of the atmosphere of the light collecting optical means is adjusted so that the film thickness of the protective film is within a predetermined range. .
(12) In the above (9), the protective film material supply means is used as a protective film material gas supply means to monitor the film thickness of the protective film of the light collecting optical means, and the film thickness of the protective film is within a predetermined range. The amount of gas introduced from the protective film material gas supply means is controlled so as to be within the range.

In the present invention, the following effects can be obtained.
(1) By applying a protective film having a high transmittance to the EUV light on the reflecting film surface of the condensing optical means for condensing the EUV light, the EUV light applied to the surface of the condensing optical means Debris does not reach the reflective film with high reflectivity. For this reason, the reflective film is not damaged, and the reflectance of the condensing optical means with respect to the EUV light is maintained.
In particular, when the gas is introduced into the debris scattering path at a pressure of 100 Pa or less, it is possible to further extend the life of the EUV collector mirror.
(2) By providing a protective film material supply means and supplying a protective film material such as Si or Sr to the condensing optical means, the protective film gradually becomes thinner due to elastic collision between the debris and the protective film. However, the protective film can be restored to a predetermined thickness, and the life of the condensing optical means can be further extended.
In particular, the thickness of the protective film is monitored, and when this film thickness becomes thinner than a predetermined thickness, the protective film is kept at a predetermined thickness or more by supplying a protective film material to the condensed light means. Can do.
(3) The protective film material supply means is composed of a protective film material such as solid Si and a heating device that heats the protective film material, and condensing light by controlling power consumption and operating time of the heating device. It becomes possible to control the film thickness of the protective film deposited on the surface of the optical means.
(4) The heating means is the heating / excitation means and / or the preionization means, and a protective film is formed by the heat radiation from the discharge generated between the first and second main discharges and the creeping discharge generated in the preionization unit. By evaporating the material and supplying it to the condensing optical means, a heating device is not required separately, and the configuration becomes simple.
In this case, it is possible to control the film thickness of the protective film deposited on the surface of the condensing optical means by controlling the pressure of the atmosphere of the condensing optical means.
(5) By providing the protective film material supply means with a material replenishing means for replenishing the protective film material, and by configuring the protective film material disposed in the vicinity of the discharge part so that it can be supplied at any time without opening the chamber, The protective film material can be replenished without stopping the operation of the extreme ultraviolet light source device.
(6) The protective film material supply means is a protective film material gas supply means, and a gaseous protective film material is supplied and deposited on the EUV collector mirror surface by controlling the flow rate of the gaseous protective film material. It is possible to control the thickness of the Si film that is a protective film.
Further, similarly to the above (5), the protective film material can be supplied at any time without opening the chamber.
(7) By providing the protective film material supply means on the light incident side of the condensing optical means, the protective film material can be effectively supplied to the condensing optical means.

Hereinafter, specific embodiments of the present invention will be described.
1. Apparatus Configuration In the present invention, as described above, the protective film having a high transmittance with respect to the EUV light is applied to the reflective film surface of the condensing optical means to suppress the damage to the reflective film. As described in the first embodiment, the surface of the reflective film of the EUV collector mirror can be applied in advance by sputtering or the like before the EUV light source device is operated.
However, the protective film gradually becomes thinner due to the elastic collision between the debris and the protective film. Therefore, as will be described in the second and subsequent embodiments, a protective film material supply means for supplying a protective film material to the EUV collector mirror is provided, and the protective film is provided on the EUV collector mirror during operation of the EUV light source device. It is also possible to supply the material.
(1) First Example In the first example of the present invention, for example, in the DPP type EUV light source apparatus shown in FIG. 23, sputtering is performed on the reflective film surface of the condensing optical means (EUV condensing mirror 3). By applying a protective film having a high transmittance with respect to EUV light, etc., damage to the reflective film is suppressed.
That is, as described above, a metal film such as ruthenium (Ru), molybdenum (Mo), and rhodium (Rh) is densely coated on the reflective surface side of the base material having a smooth surface made of nickel (Ni) or the like. In the oblique incidence type condensing optical means having the reflection film formed as described above, a protective film is further provided on the surface of the reflection film. For example, silicon (Si) or strontium (Sr) is preferably used as the protective film.
When debris caused by EUV radiation species collides with the EUV collector mirror, the debris gradually scrapes the protective film or is injected into the protective film. While the protective film exists, Debris does not reach the reflective film applied to the surface of the EUV collector mirror having a high reflectance.
For this reason, the reflective film of the EUV collector mirror is not damaged, and the reflectance of the EUV collector mirror with respect to the EUV light is maintained.

In particular, if a protective film is provided on the EUV collector mirror as described above and gas is introduced into the debris scattering path at a pressure of 100 Pa or less, it is possible to further extend the life of the EUV collector mirror. It becomes. Therefore, the gas exhaust unit 12 in FIG. 23 is controlled so that the pressure in the second container 1b is 100 Pa or less.
By providing a protective film on the EUV collector mirror, the EUV collector can be used even when operating continuously as a light source for an exposure apparatus for a long period of time, compared to simply introducing gas into the scattering path at a pressure of 100 Pa or less. It is possible to provide an EUV light source device that further suppresses damage to the reflective film of the optical mirror and realizes a long lifetime of the EUV collector mirror.
FIG. 1A shows the relationship between the thickness of the silicon film and the transmittance of EUV light having a wavelength of 13.5 nm. FIG. 1B shows the relationship between the thickness of the strontium film and the transmittance of EUV light having a wavelength of 13.5 nm.
As is apparent from FIG. 1, the transmittance of EUV light (wavelength 13.5 nm) is 80% or more when the film thickness of the Si film or Sr film is 100 nm or less. Therefore, when a Si film or Sr film is employed as the protective film, the film thickness is desirably set to 100 nm or less.

(2) Second Embodiment In the first embodiment described above, the life of the EUV collector mirror can be extended by providing a protective film on the reflective surface of the EUV collector mirror. In the embodiment described below, the film thickness of the protective film that is scraped by debris caused by EUV radiation species that are fast ions or neutral atoms is monitored, and when this film thickness becomes thinner than a predetermined film thickness, The protective film material is supplied to the EUV collector mirror so that the film thickness of the protective film does not fall below a certain thickness. As a result, the life of the EUV collector mirror can be further extended.
First, a second embodiment of the present invention of an EUV light source apparatus having a protective film material supply function will be described.
In this embodiment, a protective film material supply device comprising a protective film material and heating means for heating and evaporating the protective film material is added to the EUV light source device.

FIG. 2 shows the configuration of the EUV light source apparatus of this embodiment.
In this embodiment, in addition to the structure shown in FIG. 23, a protective film material supply device 20 including a protective film material 21 and a heating device 22 is provided. The installation position of the protective film material supply device 20 is set in at least one of the second container 1b and the first container 1a in the vicinity of the EUV collector mirror 3. In FIG. 2, protective film material supply devices 20-1 and 20-2 are installed in both the first container 1a and the second container 1b.

Other configurations are the same as those shown in FIG. 23, and the same components as those shown in FIG. 23 are denoted by the same reference numerals.
That is, as described above, in the chamber 1 that is a discharge vessel, for example, a ring-shaped first main discharge electrode 2a (cathode) and a second main discharge electrode 2b (anode) are ring-shaped insulating materials. It arrange | positions on both sides of 2c.
The chamber 1 is composed of a first container 1a formed of a conductive material and a second container 1b formed of the same conductive material. The first container 1a and the second container 1b are: It is separated and insulated by the insulating material 2c.
The ring-shaped first main discharge electrode 2a, the second main discharge electrode 2b, and the insulating material 2c are arranged so that the respective through holes are positioned substantially on the same axis, and constitute communication holes. The second main discharge electrodes 2a and 2b are connected by a high voltage pulse generator 14 supplied with pulse power.

A raw material containing EUV radioactive species is supplied into the chamber 1 from a raw material supply unit 9 connected to a raw material inlet 10 provided on the first container 1 a side of the chamber 1. Examples of the raw material include SnH ₄ gas and Xe gas.
Further, a preionization unit 8 is provided above and coaxially with the high density high temperature plasma generation unit 11 so as to effectively preionize the raw material containing EUV radiation species existing in the high density high temperature plasma generation unit 11. ing. The preionization unit 8 includes a first preionization member 8a and a second preionization member 8c made of a cylindrical conductive material, and a first preionization member 8a and a second preionization member 8c made of a cylindrical insulating material. It consists of a preionization insulating material 8b disposed so as to be sandwiched between the preionization member 8c.
The conductive second preionization member 8 c is connected to one terminal of the preionization power supply unit 13. Note that the other terminal of the preionization power supply unit 13 is connected to the conductive first preionization member 8a via the conductive first container 1a.

A gas exhaust unit 12 for adjusting the pressure in the chamber 1 and exhausting the chamber based on the measurement value of the pressure monitor 7 for monitoring the pressure in the chamber is provided on the second container 1b side of the chamber 1. Connected to the outlet 5.
In addition, the EUV collector mirror 3 is provided in the second container 1b, and the EUV collector mirror 3 is a reflective surface of a base material having a smooth surface made of, for example, nickel (Ni) as described above. On the side, a metal film such as ruthenium (Ru), molybdenum (Mo), and rhodium (Rh) is densely coated, and obliquely configured so that EUV light with an oblique incident angle of 0 ° to 25 ° can be reflected well. This is an incident type condensing optical means.
In addition, as described above, between the high-density and high-temperature plasma region and the EUV collector mirror 3, debris such as metal powder or debris caused by a radioactive species such as Sn is captured and only EUV light is allowed to pass. A debris trap 4 is installed.

The protective film material 21 of this embodiment is, for example, solid Si or Sr, and is heated by the heating device 22. Of the Si and Sr vaporized by heating, the one that reaches the surface of the EUV collector mirror 3 and is adsorbed is deposited on the surface of the EUV collector mirror 3. Therefore, the film thickness of the Si film or Sr film, which is a protective film deposited on the surface of the EUV collector mirror, can be controlled by controlling the power consumption and operating time of the heating device 22.
As a heating method, the protective film material 21 may be heated by heater heating, or the protective film material 22 may be heated by energization heating.
In FIG. 2, the example which employ | adopted the electrical heating in the protective film material supply apparatus 20-1 installed in the 1st container 1a is shown. On the other hand, the example which employ | adopted heater heating in the protective film material supply apparatus 20-2 installed in the 2nd container 1b is shown.

The monitor unit 23 detects the deposition status of a protective film (for example, Si film or Sr film) deposited on the EUV collector mirror 3. The monitor unit 23 is, for example, a crystal oscillator type film thickness monitor, and is disposed in the vicinity of the EUV collector mirror 3 and at a position off the optical path of the EUV light.
That is, the deposition state of the protective film on the reflection surface of the EUV collector mirror 3 is detected by detecting the amount of deposits deposited on the film thickness monitor disposed in the vicinity of the EUV collector mirror 3.
A detection signal from the monitor unit 23 is sent to the film thickness measuring means 24. Based on the received detection signal, the film thickness measuring unit 24 calculates the film thickness, deposition rate, and the like of the protective film deposited on the EUV collector mirror 3. This calculation result is sent from the film thickness measuring means 24 to the control unit 30.
The control unit 30 controls the protective film material supply devices 20-1 and 20-2 based on the protective film thickness data and the protective film deposition rate data sent from the film thickness measuring means 24. A specific control procedure will be described later.
The protective film material supply device 20 may be installed at any position on the containers 1a and 1b, but by providing the protective film material supply device 20 on the light incident side of the EUV collector mirror 3. The protective film material can be effectively supplied to the EUV collector mirror 3.

As described above, in this embodiment, the film thickness of the protective film is monitored, and when the film thickness becomes thinner than a predetermined film thickness, a protective film material such as Si or Sr is supplied to the EUV collector mirror 3. Therefore, the thickness of the protective film can be kept at a predetermined thickness or more, and the life of the condensing optical means can be extended.
In particular, the protective film material supply device means is composed of a protective film material such as solid Si and a heating device for heating this, and condensing optics by controlling the power consumption and operating time of the heating device. It becomes possible to control the thickness of the protective film deposited on the surface of the means.

(3) Third Embodiment The EUV light source apparatus according to the third embodiment of the present invention does not supply the protective film material by the heating device unlike the EUV light source apparatus according to the second embodiment. The protective film material is supplied by utilizing the discharge generated between the second main discharge electrodes 2a and 2b and the creeping discharge generated in the preionization unit 8.
FIG. 3 shows an example of the configuration. In this embodiment, the heating means 22 shown in the first embodiment is not provided. Instead, the protective film material 21 is in the vicinity of a portion where plasma is formed by the discharge between the main discharge electrodes 2a and 2b. And / or a region where creeping discharge of the preliminary ionization unit 8 occurs or in the vicinity thereof.
Other configurations are the same as those in FIG. 2, and the same components are denoted by the same reference numerals.

In FIG. 3, the ring-shaped first main discharge electrode 2a, second main discharge electrode 2b, and insulating material 2c arranged substantially coaxially form a communication hole in the same manner as that shown in FIG. When pulse power is supplied from the high voltage pulse generator 14 between the first and second main discharge electrodes, creeping discharge is generated on the surface of the insulating material, and plasma is formed in the communication hole or in the vicinity of the communication hole. .
As described above, Joule heating by the pinch effect forms a high-density and high-temperature plasma at the substantially central portion of the plasma, and EUV light having a wavelength of 13.5 nm is emitted from the high-density and high-temperature plasma. The space in which the above-described creeping discharge is generated and plasma is formed is hereinafter referred to as a discharge portion.
In the present embodiment, the protective film material 21 is disposed in the vicinity of the discharge portion. The arrangement position of the protective film material 21 in the vicinity of the discharge part is, for example, the surface of the insulating material 2 c facing the discharge part or the upper surface of the debris trap 4. FIG. 3 shows an example in which the protective film material 21 is disposed on both the surface of the insulating material 2 c facing the discharge portion and the upper surface of the debris trap 4.
Note that the protective film material 21 is not necessarily disposed on both sides, and may be disposed on at least one of the surface of the insulating material 2 c and the upper surface of the debris trap 4.
In the present embodiment, the protective film material is disposed in an area where creeping discharge occurs in the preliminary ionization unit 8 or in an arbitrary position near the area.

In FIG. 3, the protective film material 21 is disposed on the preionization insulating material 8b, but the present invention is not limited to this arrangement. For example, you may arrange | position in the creeping discharge area vicinity like the edge part of the insulating material 8b for preliminary | backup ionization.
Here, FIG. 3 shows an example in which the protective film material 21 is disposed in the vicinity of the discharge portion and in the vicinity of the creeping discharge of the preliminary ionization unit 8. However, the protective film material 21 does not necessarily need to be disposed on both sides, and may be disposed in at least one of the vicinity of the discharge portion and the vicinity of the creeping discharge of the preliminary ionization unit 8.
For example, silicon carbide (SiC) or silicon nitride (Si ₃ N ₄ ) is used as the protective film material 21. These protective film materials 21 are evaporated and decomposed by radiant heat from the discharge part and the creeping discharge, and a part thereof becomes vaporized Si. The vaporized Si that has reached the surface of the EUV collector mirror is deposited on the surface of the reflective film of the EUV collector mirror 3.

As the protective film material 21, solid Si or Sr can also be used. However, since the heating by the radiant heat from the discharge part or the creeping discharge is a heating performed at a higher temperature than the heater heating or the energization heating in the second embodiment, for example, in the case of solid Si, the heating is performed in a relatively short time. Disappears. Therefore, as the protective film material, a material having relatively high heat resistance, such as silicon carbide (SiC) or silicon nitride (Si ₃ N ₄ ), which vaporizes little by little even when heated by the radiant heat is preferable.
Here, the EUV collector mirror 3 may deposit C, C compounds, N, and N compounds in addition to Si. However, according to the experiments by the inventors, the deposit was predominantly Si, and the C component and N component were slight. And the EUV transmittance of the deposit was almost the same as that of Si alone.

By the way, the deposition rate of Si deposited on the reflecting surface of the EUV collector mirror 3 by the mechanism as described above depends on the pressure in the second container 1b in which the EUV collector mirror 3 is installed. That is, when the pressure is low, the rate at which debris (high-speed ions or neutral atoms) caused by the EUV radiation species reaches and collides with the EUV collector mirror 3 increases, and the deposition rate of Si is low. On the other hand, when the pressure is high, the rate at which the debris caused by the EUV radiation species reaches and collides with the EUV collector mirror 3 is small, and the deposition rate of Si is high.
Therefore, it is possible to control the film thickness of the Si film that is a protective film deposited on the surface of the EUV collector mirror 3 by controlling the pressure in the second container 1b where the EUV collector mirror 3 is installed. Become. The monitor unit 23 detects the deposition state of a protective film (for example, Si film) deposited on the EUV collector mirror 3 as in the first embodiment.
As described above, the monitor unit 23 is, for example, a crystal oscillator type film thickness monitor, and is disposed in the vicinity of the EUV collector mirror 3 and at a position off the optical path of the EUV light. And the deposition state of the protective film on the reflective surface of the EUV collector mirror 3 is detected by detecting the amount of deposits deposited on the film thickness monitor 23 arranged in the vicinity of the EUV collector mirror 3.

A detection signal from the monitor unit 23 is sent to the film thickness measuring means 24. Based on the received detection signal, the film thickness measuring unit 24 calculates the film thickness, deposition rate, and the like of the protective film deposited on the EUV collector mirror 3. This calculation result is sent from the film thickness measuring means 24 to the control unit 30.
The control unit 30 controls the exhaust amount from the gas exhaust unit 12 while referring to the pressure data from the pressure monitor 7 based on the protective film thickness data and the protective film deposition rate data sent from the film thickness measuring means 24. Then, the pressure in the second container 1b in which the EUV collector mirror 3 is installed is controlled.
Alternatively, for example, when supplying a raw material gas containing EUV radioactive species (for example, Xe gas) and a buffer gas as a raw material containing EUV radioactive species, an EUV collector mirror is installed by controlling the buffer gas flow rate. It is also possible to control the pressure in the second container.
Thereby, the film thickness of the protective film on the reflective surface of the EUV collector mirror 3 is controlled to be equal to or greater than a desired thickness. A specific control procedure will be described later.
In this embodiment, as described above, the thickness of the protective film is monitored, and when this film thickness becomes thinner than a predetermined film thickness, a protective film material such as Si or Sr is supplied to the EUV collector mirror 3. Therefore, similarly to the above-described embodiment, the protective film can be kept at a predetermined thickness or more, and the life of the condensing optical means can be extended.
In particular, without providing a heating means, the protective film material is evaporated by heat radiation from plasma generated by the discharge generated between the first and second main discharge electrodes 2a and 2b or creeping discharge generated in the preliminary ionization unit 8. By supplying the light to the condensing optical means, a heating device is not required separately, and the configuration becomes simple.

(4) Fourth Embodiment In the second and third embodiments, the protective film material 21 installed in the chamber 1 is vaporized by radiant heat from heating or discharge by the heating means 22 to collect EUV light. A protective film is deposited on the reflecting surface of the mirror 3. Therefore, when all of the protective film material 21 is vaporized, it is necessary to open the chamber 1 and newly set the protective film material.
If it is necessary to make settings other than during maintenance and inspection (for example, replacement of the first and second main discharge electrodes 2a and 2b), the exposure process must be stopped.
The EUV light source apparatus according to the present embodiment employs a structure capable of supplying the protective film material 21 without opening the chamber 1.
FIG. 4 shows an example of the configuration. In FIG. 4, in the EUV light source device of the second embodiment, a moving mechanism 25 for feeding the protective film material into the chamber is provided, and the protective film material 21 disposed in the vicinity of the discharge portion is disposed at any time without opening the chamber. The other configurations are the same as those shown in FIGS. 2 and 3, and the same components are denoted by the same reference numerals.

The protective film material 21 is made of, for example, silicon carbide (SiC) or silicon nitride (Si ₃ N ₄ ), as in the EUV light source device of the third embodiment, and is evaporated and decomposed by radiant heat from the discharge part. Part of it becomes vaporized Si. The vaporized Si that reaches the surface of the EUV collector mirror 3 is deposited on the surface of the reflective film of the EUV collector mirror 3.
The protective film material 21 is formed in, for example, a cylindrical shape and is disposed so as to penetrate the insulating material 2c. One end surface of the cylindrical protective film material 21 faces the discharge portion. On the other hand, the other end surface is connected to the moving mechanism 25.
The moving mechanism 25 moves the columnar protective film material 21 penetrating the insulating material 2c in a direction approaching the discharge portion. The columnar protective film member 21 is positioned by the moving mechanism 25 so that one end facing the discharge portion partially protrudes from the insulating material 2c.
The insulating material 2c is provided with a through hole through which the moving mechanism 25 passes, and a seal portion 26 is provided between the cylindrical protective film material and the insulating material. That is, a plurality of O-ring grooves are provided coaxially with the through hole. An O-ring is disposed in the O-ring groove. The O-ring forms a seal portion 26 that seals between the cylindrical protective film material and the insulating material, and keeps the inside of the chamber 1 airtight.
Since the cylindrical protective film member moves while being in contact with the O-ring, gas leakage is likely to occur during movement. In order to suppress such a leak, a plurality of seal portions 26 each including an O-ring groove and an O-ring are provided for the columnar protective film member.

  Here, FIG. 4 shows a structure in which the protective film material 21 is supplied to the vicinity of the discharge portion through the insulating material 2c. However, the protective film material 21 does not need to penetrate the insulating material 2c. For example, the protective film material 21 may be configured to penetrate the second container 1b and supply the upper surface of the debris trap 4 near the protective film. Alternatively, the first container 1 a may be penetrated and supplied to the vicinity of the creeping discharge of the preliminary ionization unit 8.

The protective film material 21 in the EUV light source device of this embodiment is deposited on the reflective film surface of the EUV collector mirror 3 by the same mechanism as that of the third embodiment. Therefore, the deposition rate of Si deposited on the reflecting surface of the EUV collector mirror 3 depends on the pressure in the second container 1b in which the EUV collector mirror 3 is installed, as in the third embodiment. .
That is, when the pressure is low, the rate at which debris (high-speed ions or neutral atoms) caused by the EUV radiation species reaches and collides with the EUV collector mirror 3 increases, and the deposition rate of Si is low. On the other hand, when the pressure is high, the rate at which the debris caused by the EUV radiation species reaches and collides with the EUV collector mirror 3 is small, and the deposition rate of Si is high.
Therefore, by controlling the pressure in the second container 1b in which the EUV collector mirror 3 is installed, it becomes possible to control the thickness of the Si film that is a protective film deposited on the surface of the EUV collector mirror. .

That is, the thickness of the protective film is controlled as follows.
As in the third embodiment, a detection signal from the monitor unit 23 is sent to the film thickness measuring means 24. Based on the received detection signal, the film thickness measuring unit 24 calculates the film thickness, deposition rate, and the like of the protective film deposited on the EUV collector mirror 3. This calculation result is sent from the film thickness measuring means 24 to the control unit 30.
The control unit 30 controls the exhaust amount from the gas exhaust unit 12 while referring to the pressure data from the pressure monitor 7 based on the protective film thickness data and the protective film deposition rate data sent from the film thickness measuring means 24. Then, the pressure in the second container in which the EUV collector mirror 3 is installed is controlled. A specific control procedure will be described later.

Here, the control unit 30 stores in advance disappearance rate data by vaporization of the cylindrical protective film material 21. This disappearance rate data is obtained in advance by actual measurement or calculation based on radiant heat data from the discharge part or the like. Based on the disappearance rate data, the control unit 30 calculates, for example, the protruding amount of the cylindrical protective film material 21 protruding from the insulating material 2c with respect to the discharge unit as needed. When the projection amount reaches a predetermined amount or less and reaches a threshold value where it is difficult to supply the protective film material 21 to the condenser mirror 3, the moving mechanism 25 is driven to insulate the discharge portion from the insulating material. Control is performed so that the protruding amount of the cylindrical protective film material 21 protruding from 2c is larger than the above threshold.
Specifically, one end surface of the cylindrical protective film material 21 penetrating the insulating material 2c is faced to the discharge portion, and the moving mechanism 25 positions the one end facing the discharge portion so as to partially protrude from the insulating material 2c. . When the protruding portion of the cylindrical protective film material 21 is vaporized and consumed due to the radiant heat generated by the discharge, and it becomes difficult to supply the protective film material to the condensing mirror 3, one end facing the discharge portion is removed from the insulating material 2c. Then, it is positioned by the moving mechanism 25 so as to partially protrude again.
Therefore, according to this embodiment, when all of the protective film material is vaporized, the exposure process is stopped, the chamber is opened, and the protective film material installed in the chamber must be set. can do.

(5) Fifth Embodiment In the second to fourth embodiments, the solid protective film material 21 is supplied into the chamber 1 and is vaporized by radiant heat from heating or discharge by the heating means 22. The EUV collector mirror 3 is configured to be deposited as a protective film on the reflecting surface.
On the other hand, in this embodiment, a solid protective film material is not supplied, but a gaseous protective film material is supplied.
FIG. 5 shows an example of the configuration. 5, instead of the protective film material 21 and the moving mechanism 25 in the EUV light source device shown in FIG. 4, a protective film material gas supply unit 27 is provided to supply a gaseous protective film material. There are other configurations similar to those shown in the embodiment.
The protective film material gas is supplied from the protective film material supply unit 27 to the vicinity of the reflection surface of the EUV collector mirror through the nozzle 27a penetrating the second container 1b.

When a Si film is used as the protective film, a silane gas such as silane (SiH ₄ ), disilane (Si ₂ H ₆ ), or trisilane (Si ₃ H ₈ ) is used as the protective film material gas. The light absorption edges (absorption wavelengths) of silane, disilane, and trisilane are about 160 nm, about 190 nm, and about 205 nm, respectively.
Further, the bond energy of Si—H is 3.6 eV, which is 345 nm at a wavelength converted from photon energy. That is, the Si—H bond is broken when light having a wavelength shorter than 345 nm is absorbed.
Therefore, when silane is used as the protective film material gas, when the silane is irradiated with light having a wavelength of 160 nm or less, the light is absorbed by the silane, and the Si—H bond of the silane is cut and decomposed. The chemical reaction formula at this time is represented by the following formula.
SiH ₄ + hν (λ = 160 nm or less) → Si + 2H ₂
Here, hν is the energy of light (h is Planck's constant, ν is the frequency of light).

The EUV light source device of this embodiment uses a silane-based gas as a protective film material gas. For example, when the protective film material gas is silane, silane is introduced in the vicinity of the reflective film surface of the EUV collector mirror 3, and the silane is irradiated with light having a wavelength of 160 nm or less to cut Si—H bonds, and Si and Gives H ₂ . Si generated by this chemical reaction is deposited on the reflective film surface of the EUV collector mirror 3 as a protective film.
As described above, the raw material (for example, Xe gas, SnH ₄ gas, etc.) containing the EUV radiation species introduced into the chamber generates EUV light through the processes of heating, ionization, and excitation. In this radiation process, various energy transitions that emit light of various wavelengths occur. That is, the light emitted from the EUV light source device includes not only EUV light having a wavelength of 13.5 nm necessary for exposure but also light in the ultraviolet region and vacuum ultraviolet region.
That is, light having a wavelength of 205 nm or less, a wavelength of 190 nm or less, and a wavelength of 160 nm or less is also included.
Therefore, when silane-based gas is introduced in the vicinity of the reflective film surface of the EUV collector mirror, light in the ultraviolet region and vacuum ultraviolet region emitted from the plasma when EUV is generated reaches the vicinity of the reflective film surface of the EUV collector mirror. A decomposition reaction of the silane-based gas occurs, and as a result, a Si film can be formed as a protective film on the reflective surface of the EUV collector mirror.

The film thickness of the Si film in the EUV light source device of the present embodiment depends on the supply amount of the protective film material gas. Therefore, by controlling the supply amount of the protective film material gas supplied from the protective film material gas supply unit 27, the film thickness of the Si film that is a protective film deposited on the surface of the EUV collector mirror 3 can be controlled. It becomes possible.
That is, as described above, the detection signal from the monitor unit 23 is sent to the film thickness measuring means 24. Based on the received detection signal, the film thickness measuring unit 24 calculates the film thickness, deposition rate, and the like of the protective film deposited on the EUV collector mirror 3. This calculation result is sent from the film thickness measuring means 24 to the control unit 30.
The control unit 30 controls the supply amount of the protective film material gas supplied from the protective film material gas supply unit 27 based on the protective film thickness data and the protective film deposition rate data sent from the film thickness measuring means 24. To do. A specific control procedure will be described later.
In this embodiment, since the gaseous protective film material is supplied and the gaseous protective film material is supplied as described above, the film thickness of the Si film that is a protective film deposited on the EUV collector mirror surface is set. In addition to being able to control, the protective film material can be supplied at any time without opening the chamber.

(6) Sixth Embodiment In the first to fifth embodiments described above, a pulse-shaped large current is provided between the ring-shaped first main discharge electrode 2a and the second main discharge electrode 2b arranged coaxially. As described above, the present invention is applied to an EUV light source device that generates high-density and high-temperature plasma. Next, the electrode and the solid or liquid state proposed by Non-Patent Document 2 are rotated and moved. An embodiment in which the present invention is applied to an EUV light source apparatus (hereinafter referred to as a rotary electrode EUV light source apparatus) that moves a raw material for high-density high-temperature plasma to a discharge portion will be described.
FIG. 6 is a cross-sectional view of the EUV light source device of this embodiment. In this embodiment, the protective film material supply device 20 shown in the second embodiment (FIG. 2) is provided in a rotary electrode EUV light source device. Shows the case.
In FIG. 6, the EUV light source apparatus of the present embodiment has a container 1a which is a discharge container. The right side of the container 1a is the side from which EUV light is emitted. The container 1 a is attached to the container 1 b provided with the EUV collector mirror 3 on the EUV light emission side.
The EUV collector mirror 3 collects the EUV light emitted from the container 1a and guides the light from the EUV light extraction unit 6 to an exposure apparatus (not shown). The space in the discharge vessel is called a discharge space, and the space in the vessel 1b provided with the EUV collector mirror 3 is called a light collection space. The discharge space and the condensing space are exhausted by the gas exhaust unit 12.
Further, the EUV light source device of the present embodiment is provided with a partition wall 40 which is divided into a discharge space and a condensing space between a container 1a which is a discharge container and a container 1b provided with the EUV condensing mirror 3. An aperture member 41 having an opening 41a for spatially connecting both spaces to the partition wall 40 is provided, and gas exhaust units 12-1 and 12-2 are connected to the discharge portion and the EUV collector mirror portion, respectively. Yes.

In the container 1a, the disc-shaped first discharge electrode 2a and the second discharge electrode 2b are spaced by sandwiching the insulating material 2c so that the centers of the circles of both the electrodes 2a and 2b coincide. That is, they are concentrically overlapped and fixed. The diameter of the second discharge electrode 2b is slightly larger than the diameter of the first discharge electrode 2a.
A high voltage pulse generator 14 is connected to the first main discharge electrode 2a and the second main discharge electrode 2b via the first and second sliders 14a and 14b, and a high voltage pulse is supplied. The Edges are formed in the periphery of the first discharge electrode 2a and the second discharge electrode 2b, and when electric power is supplied to both electrodes, a discharge is generated between the both edges.

When discharge occurs, the electrodes become high temperature, and therefore, the first discharge electrode 2a and the second discharge electrode 2b are made of a refractory metal such as tungsten, molybdenum, or tantalum. The insulating material 2c is made of, for example, silicon nitride, aluminum nitride, diamond, or the like.
A rotation shaft 42a is attached to the center of the second discharge electrode 2b, and the first discharge electrode 2a, the insulating material 2c, and the second discharge electrode 2a are integrally formed by a motor 42 attached to the rotation shaft 42a. Rotate.
On the opposite side of the EUV light emission side in the container 1a, there is a raw material supply unit 9 for supplying the raw material of the EUV generation species to the electrode 2b.
The raw material supply unit 9 supplies solid Li or Sn, which is a raw material of the EUV generation species, to the peripheral portion 2d of the second discharge electrode 2b rotated by the motor 41.

The electrode portion to which Li or Sn is supplied by the raw material supply unit 9 rotates and moves to the EUV light emission side. A laser irradiator 43 is provided on the EUV light emission side of the container 1a, and irradiates laser light to Li or Sn supplied to the peripheral portion 2d of the second discharge electrode 2b.
As described above, since the second discharge electrode 2b has a larger diameter than the first discharge electrode 2a, the laser light is irradiated to the peripheral portion of the second discharge electrode 2b through the first discharge electrode 2a. The Li or Sn is vaporized by laser irradiation.
In such a state, a high voltage pulse voltage of approximately +20 kV to −20 kV is applied to both electrodes 2 a and 2 b from the high voltage pulse generator 14.
A discharge occurs between the edges of both electrodes, and a large pulsed current flows. Thereafter, Joule heating due to the pinch effect generates high-density and high-temperature plasma by vaporized Li or Sn in the peripheral part between both electrodes, and EUV light having a wavelength of 13.5 nm is emitted from this plasma.
The emitted EUV light is reflected and collected by the EUV collector mirror 3 provided in the container 1b, and emitted from the EUV light extraction unit 6 to an irradiation unit which is an exposure unit side optical system (not shown).

In the EUV light source device having the above-described configuration, in this embodiment, the protective film material supply device 20 shown in the second embodiment is provided between the debris trap 4 and the EUV collector mirror 3.
The protective film material 21 of this embodiment is, for example, solid Si or Sr as in the second embodiment, and is heated by the heating device 22. Of the Si and Sr vaporized by heating, the one that reaches the surface of the EUV collector mirror 3 and is adsorbed is deposited on the surface of the EUV collector mirror 3.
Therefore, it is possible to control the film thickness of the Si film or Sr film, which is a protective film deposited on the surface of the EUV collector mirror, by controlling the power consumption and operating time of the heating device 22 as described above. . Although FIG. 6 shows the case where the protective film material 21 is heated by heater heating, the protective film material 22 may be heated by energization heating.

(7) Seventh Embodiment Next, an embodiment in which the fifth embodiment (FIG. 5) of the present invention is applied to the rotating electrode type EUV light source apparatus will be described.
FIG. 7 is a cross-sectional view of the EUV light source apparatus of this embodiment.
In this embodiment, a protective film material gas supply unit 27 is provided between the EUV collector mirror 3 and the debris trap 4 to supply a gaseous protective film material. The protective film material gas is supplied from the protective film material supply unit 27 to the vicinity of the reflecting surface of the EUV collector mirror 3 through the nozzle 27a penetrating the second container 1b.
In addition, since the opening 41a of the aperture member 41 functions as a pressure resistance, even if a gaseous protective film material is supplied in the condensing space by exhausting each space with the gas exhaust units 12-a and 12-2. The condensing space can be maintained at several hundred Pa and the discharge space can be maintained at several Pa.

The other configuration is the same as that shown in FIG. 6, and a rotating disk-shaped first discharge electrode 2a and a second discharge electrode 2b are provided in the container 1a. When a voltage pulse is supplied, a discharge occurs between the edges of the peripheral portions of the first discharge electrode 2a and the second discharge electrode 2b, and a large pulse current flows. As a result, the laser beam from the laser irradiator 43 is condensed at the peripheral part between both electrodes, and high-density and high-temperature plasma is generated by Li or Sn vaporized by heating. Is done.
The emitted EUV light is reflected and collected by the EUV collector mirror 3 provided in the container 1 b, and is emitted from the EUV light extraction unit 6.
In the present embodiment, the protection deposited on the surface of the EUV collector mirror 3 is controlled by controlling the supply amount of the protective film material gas supplied from the protective film material gas supply unit 27 as in the fifth embodiment. It becomes possible to control the film thickness.
Further, the protective film material can be supplied at any time without opening the chamber.
In the sixth and seventh embodiments, the case where the rotating electrode type EUV light source apparatus is applied to the second embodiment (FIG. 3) and the fifth embodiment (FIG. 5) has been described. The third to fourth embodiments can also be applied to a rotating electrode type EUV light source apparatus.
In this case, as described above, the film thickness of the Si film that is a protective film deposited on the surface of the EUV collector mirror 3 is controlled by controlling the pressure in the second container 1b in which the EUV collector mirror 3 is installed. Can be controlled.

2. Control Example Next, a control example of the above-described EUV light source device will be described.
(8) Eighth Embodiment This embodiment shows a control example of the EUV light source device shown in the second embodiment (FIG. 2). FIGS. 8 and 9 are flowcharts of this embodiment, and FIG. Shows the time chart.
Here, the initial state of the surface of the EUV collector mirror is a state in which a protective film having a predetermined thickness is applied in advance. The above-mentioned predetermined film thickness is a ratio of the reflectance of the EUV light when the protective film is present on the reflection surface to the reflectance when there is no protective film in the EUV collector mirror is a predetermined value or more. It is the film thickness when. For example, the predetermined film thickness is set so that the ratio is 80% or more.
Hereinafter, the control method of the present embodiment will be described.
A standby signal is sent from the controller 31 of the exposure machine to the controller 30 of the EUV light source device (step S101 in FIG. 8, FIG. 10A).

The control unit 30 of the EUV light source apparatus that has received the standby signal controls the raw material supply unit 9 so that the raw material supply amount becomes a predetermined amount. For example, when the raw material is Xe gas, the Xe gas flow rate is controlled to be a predetermined value (step S102, FIGS. 10G and 10H).
Based on the pressure data sent from the pressure monitor 7, the control unit 30 of the EUV light source device controls the gas exhaust unit 12 so that the pressure of the high-density and high-temperature plasma generation unit 11 becomes a predetermined pressure (for example, 1 to 20 Pa). Control to adjust the gas exhaust amount (step S103, FIG. 10 (i)).
The control unit 30 of the EUV light source apparatus sends a standby completion signal to the control unit 31 of the exposure machine (step S104).
Upon receiving the standby completion signal, the controller 31 of the exposure apparatus sends out an EUV light emission command signal to the controller 30 of the EUV light source device (step S105, FIG. 10B).
Upon receiving the EUV light emission command signal, the control unit 30 of the EUV light source device controls the preliminary ionization power supply unit 13 to supply power to the preliminary ionization unit 8 and operates the preliminary ionization unit 8 to perform preliminary ionization. A trigger signal is sent to the voltage pulse generator 14 (step S106, FIGS. 10 (k) (l)).
Further, the control unit 30 of the EUV light source apparatus starts the operation of the monitor unit 23 (step S107, FIG. 10 (j)).

The high voltage pulse generator 14 that has received the trigger signal applies pulse power between the first main discharge electrode (cathode) 2a and the second main electrode (anode) 2b. A creeping discharge is generated on the surface of the insulating material 2c, and the first main discharge electrode 2a and the second main discharge electrode 2b are substantially short-circuited. The first main discharge electrode 2a and the second main discharge electrode 2b A large pulse current flows between the main discharge electrodes 2b. Thereafter, high-density and high-temperature plasma is generated in the high-density and high-temperature plasma generator 11 by Joule heating due to the pinch effect, and EUV light having a wavelength of 13.5 nm is emitted from the plasma (FIG. 10 (m)).
The emitted EUV light is reflected by the EUV collector mirror 3 provided on the second main discharge electrode side 2b (anode), and from the EUV light extraction unit 6 including wavelength selection means (for example, an optical filter), The light is emitted to an irradiation unit (not shown) which is an exposure machine side optical system (step S108).
After the EUV emission, a detection signal from the monitor unit 23 is sent to the film thickness measuring means 24 (step S109).
The film thickness measuring unit 24 calculates the film thickness tc of the protective film in the EUV light source device based on the received detection signal, and sends the calculation result to the control unit 30 of the EUV light source device (step S110).

The control unit 30 of the EUV light source device stores in advance threshold values t1 and t2 of the protective film thickness. The threshold value t1 of the film thickness is such that, in the EUV collector mirror 3, the ratio between the reflectance of the EUV light when the protective film is present on the reflecting surface and the reflectance when there is no protective film is a predetermined value or more. Threshold. For example, the threshold value t1 is set to the thickness of the protective film when the ratio is 80%.
When the thickness of the protective film exceeds t1, the above ratio is less than 80%, and the intensity of EUV light emitted from the EUV light source device to the exposure machine decreases.
On the other hand, the threshold value t2 of the deposition amount is a limit value when damage due to debris (high-speed ions or neutral atoms) caused by EUV radiation species occurs in the reflective film on the surface of the EUV collector mirror 3. That is, when the film thickness of the protective film falls below the threshold value t2, the reflective film on the surface of the EUV collector mirror is damaged by debris caused by EUV radiation species.
The control unit 30 of the EUV light source apparatus that has received the calculated deposition amount data from the film thickness measuring means 24 in step S110 examines the magnitude of the calculated deposition amount tc and the threshold values t1 and t2 (step S111 in FIG. 9). In step S111, when t2 <tc <t1, the process proceeds to step S112. When tc ≦ t2, the process proceeds to step S113. When t1 ≦ tc, the process proceeds to step S114.

When t2 <tc <t1, the protective film on the surface of the EUV collector mirror 3 does not deteriorate the EUV reflectivity of the EUV collector mirror 3, and the reflective film on the surface of the EUV collector mirror is used as an EUV radiation species. It is in a state where it can be protected from the debris caused.
Therefore, in step S112, the control unit 31 of the exposure machine sends an EUV radiation stop signal (corresponding to an EUV radiation end signal when the exposure process is ended, or when the exposure process is paused) to the control unit 30 of the EUV light source device. It is verified whether or not (corresponding to an EUV radiation pause signal) is input.
That is, in step S112, it is verified whether an EUV radiation stop signal is input from the controller 31 of the exposure machine to the controller 30 of the EUV light source apparatus, and when the above signal is not input at the time of verification (when No). ) Proceeds to step S105.
On the other hand, when the above signal is input (when Yes), the end is reached. Note that the description of the EUV light source device stop process (stop of gas supply, stop of exhaust in the chamber, etc.) at the end will be omitted.

When tc ≦ t2, the thickness of the protective film on the surface of the EUV collector mirror 3 is too thin as a result of the protective film being scraped by debris (high-speed ions or neutral atoms) caused by EUV radiation species It is. That is, it is in a state where it is difficult to protect the reflective film on the surface of the EUV collector mirror from the debris caused by the EUV radiation species, and the reflective film is damaged by the debris caused by the EUV radiation species. .
Therefore, in step S113, the control unit 30 of the EUV light source apparatus sends a protective film material generation command signal to the protective film material supply apparatus shown in FIG. 1 (FIGS. 10E and 10C).
The protective film material supply device 20 that has received the protective film material generation command signal operates the heating device 22 to heat the protective film material 21 (step S115, FIG. 10 (f)). As described above, as a heating method, the protective film material 21 may be heated by heater heating, or the protective film material 21 may be heated by energization heating.
When the supply of the protective film material 21 is started in step S115, the process proceeds to step S112, where it is verified whether an EUV radiation stop signal is input from the controller 31 of the exposure machine to the controller 30 of the EUV light source device. When the signal is not input (No), the process proceeds to step S105. On the other hand, when the above signal is input (when Yes), the end is reached.

When t1 ≦ tc, the thickness of the protective film deposited on the reflective surface of the EUV collector mirror by the protective film material supply device 20 becomes too thick, and the reflectance of the EUV light when the protective film is present on the reflective surface The ratio of the reflectance when there is no protective film is less than a predetermined value (for example, 80%), and the EUV light intensity emitted from the EUV light source device to the exposure device is reduced.
Therefore, in step S114, the control unit 30 of the EUV light source apparatus sends a protective film material generation stop signal to the protective film material supply apparatus 20 shown in FIG. 2 (FIG. 10 (d)).
The protective film material supply device 20 that has received the protective film material generation stop signal stops the heating device 22 and stops the heating of the protective film material (step S116).
Since the supply of the protective film material to the reflecting surface of the EUV collector mirror 3 is stopped, the protective film is gradually scraped by debris (high-speed ions or neutral atoms) caused by the EUV radiation species, and eventually the protective film The film thickness tc is less than the threshold value t1, and the ratio between the reflectance of the EUV light when the protective film is present on the reflecting surface and the reflectance when there is no protective film exceeds a predetermined value (for example, 80%).

When the supply of the protective film material is stopped in step S116, the process proceeds to step S112, where it is verified whether an EUV radiation stop signal is input from the controller 31 of the exposure machine to the controller 30 of the EUV light source apparatus. When a signal is not input (No), the process proceeds to step S105. On the other hand, when the above signal is input (when Yes), the end is reached.
As described above, the initial state of the surface of the EUV collector mirror 3 is that the ratio between the reflectance of the EUV light when the protective film is present on the reflecting surface and the reflectance when there is no protective film is a predetermined value. This is a state in which a protective film having a thickness greater than or equal to the value is applied to the reflective film surface. Therefore, the condition of tc <t1 is satisfied at the time of the verification in the first step S111 after the EUV light source device is activated.
In the above description, the control example in the EUV light source device shown in FIG. 2 has been described. However, the control method of the present embodiment can be similarly applied to the rotating electrode type EUV light source device shown in FIG. it can.

(9) Ninth Example This example shows a control example of the EUV light source device shown in the third example (FIG. 3). FIGS. 11 and 12 are flowcharts of this example, and FIG. Shows the time chart.
Here, as described above, the initial state of the surface of the EUV collector mirror 3 is a state in which a protective film having a predetermined film thickness is applied in advance. The above-mentioned predetermined film thickness is a ratio of the reflectance of the EUV light when the protective film is present on the reflection surface to the reflectance when there is no protective film in the EUV collector mirror is a predetermined value or more. It is the film thickness when. For example, the predetermined film thickness is set so that the ratio is 80% or more.
Hereinafter, the control procedure will be described with reference to FIG. 3. After the standby signal is sent from the control unit 31 of the exposure machine to the control unit 30 of the EUV light source apparatus, the EUV light is illustrated by the EUV light extraction unit 6. The steps until the light is emitted to the irradiation unit which is the exposure machine side optical system that is not performed are the same as steps S101 to S108 in the eighth embodiment, and the description thereof is omitted.

After the EUV emission, a detection signal is sent from the monitor unit 23 to the film thickness measuring means 24 (step S109).
The film thickness measuring unit 24 calculates the film thickness tc of the protective film in the EUV light source device based on the received detection signal, and sends the calculation result to the control unit 30 of the EUV light source device (step S110). The control unit 30 of the EUV light source device stores in advance threshold values t1 and t2 of the protective film thickness. Since the film thickness thresholds t1 and t2 are the same as the film thickness thresholds t1 and t2 in the eighth embodiment, description thereof is omitted.
The control unit of the EUV light source apparatus that has received the calculated deposition amount data from the film thickness measuring means in step S110 examines the magnitude of the calculated deposition amount tc and the threshold values t1 and t2 (step S111). In step S111, when t2 <tc <t1, the process proceeds to step S112. When tc ≦ t2, the process proceeds to step S213. When t1 ≦ tc, the process proceeds to step S214.

When t2 <tc <t1, the protective film on the surface of the EUV collector mirror 3 does not deteriorate the EUV reflectivity of the EUV collector mirror, and the reflective film on the surface of the EUV collector mirror 3 is caused by the EUV radiation species. It can be protected from debris. Therefore, in step S112, the control unit 31 of the exposure machine sends an EUV radiation stop signal (corresponding to an EUV radiation end signal when the exposure process is ended, or when the exposure process is paused) to the control unit 30 of the EUV light source device. It is verified whether or not (corresponding to an EUV radiation pause signal) is input.
That is, in step S112, it is verified whether an EUV radiation stop signal is input from the controller 31 of the exposure machine to the controller 30 of the EUV light source apparatus, and when the above signal is not input at the time of verification (when No). ) Proceeds to step S105.
On the other hand, when the above signal is input (when Yes), the end is reached. Note that the description of the EUV light source device stop process (stop of gas supply, stop of exhaust in the chamber, etc.) at the end will be omitted.

When tc ≦ t2, the thickness of the protective film on the surface of the EUV collector mirror 3 became too thin as a result of the protective film being scraped by debris (fast ions or neutral atoms) caused by EUV radiation species. State. That is, it is in a state where it is difficult to protect the reflective film on the EUV collector mirror surface from debris caused by the EUV radiation species, and the reflective film is damaged by the debris caused by the EUV radiation species.
As described above, the deposition rate of Si deposited on the reflecting surface of the EUV collector mirror 3 depends on the pressure in the second container 1b where the EUV collector mirror is installed. That is, when the pressure is low, the rate at which debris (high-speed ions or neutral atoms) caused by the EUV radiation species reaches and collides with the EUV collector mirror 3 increases, and the deposition rate of Si is low. On the other hand, when the pressure is high, the rate at which debris caused by EUV radiation species reaches the EUV collector mirror and collides with it becomes small, and the deposition rate of Si is high.
Therefore, in step S213, the control unit 30 of the EUV light source apparatus sends a protective film material deposition promotion command signal to the gas exhaust unit 12 shown in FIG. 3 (FIG. 13C).
The gas exhaust unit 12 that has received the protective film material deposition promotion command signal decreases the exhaust amount per unit time and increases the pressure in the second container 1b (step S215, FIGS. 13J and 13F).

That is, the deposition rate of the protective film on the surface of the EUV collector mirror 3 is made larger than the removal rate of the protective film by debris (high-speed ions or neutral atoms) caused by the EUV radiation species, and the surface of the EUV collector mirror 3 Promote the deposition of protective films in
When the deposition of the EUV protective film material is promoted by step S215, the process proceeds to step S112, where it is verified whether an EUV radiation stop signal is input from the control unit of the exposure machine to the control unit of the EUV light source device. When the signal is not input (No), the process proceeds to step S105. On the other hand, when the above signal is input (when Yes), the end is reached. When t1 ≦ tc, the thickness of the protective film deposited on the reflective surface of the EUV collector mirror 3 becomes too thick, and the reflectance of the EUV light when the protective film is present on the reflective surface and the absence of the protective film In this state, the intensity of the EUV light emitted from the EUV light source device to the exposure device is reduced.
Therefore, in step S214, the control unit 30 of the EUV light source apparatus sends a protective film material supply stop signal to the protective film material supply apparatus 20 shown in FIG. 3 (FIG. 13 (d)).
The gas exhaust unit 12 that has received the protective film material supply stop signal increases the exhaust amount per unit time and decreases the pressure in the second container 1b (step S216). That is, the deposition rate of the protective film on the surface of the EUV collector mirror 3 is set to be smaller than the removal rate of the protective film due to debris (fast ions or neutral atoms) caused by the EUV radiation species.

Therefore, the protective film deposited on the reflective surface of the EUV collector mirror 3 is gradually scraped by debris (high-speed ions or neutral atoms) caused by the EUV radiation species, and the film thickness tc of the protective film eventually becomes the threshold value. Below t1, the ratio of the reflectance of the EUV light when the protective film is present on the reflecting surface to the reflectance when there is no protective film exceeds a predetermined value (for example, 80%).
When the supply of the protective film material is stopped in step S216, the process proceeds to step S112, where it is verified whether the EUV radiation stop signal is input from the controller 31 of the exposure machine to the controller 30 of the EUV light source apparatus. When the signal is not input (No), the process proceeds to step S105.
On the other hand, when the above signal is input (when Yes), the end is reached.
As described above, the initial state of the surface of the EUV collector mirror 3 is that the ratio between the reflectance of the EUV light when the protective film is present on the reflecting surface and the reflectance when there is no protective film is a predetermined value. This is a state in which a protective film having a thickness greater than or equal to the value is applied to the reflective film surface. Therefore, the condition of tc <t1 is satisfied at the time of the verification in the first step S111 after the EUV light source device is activated.

(10) Modification of Ninth Embodiment In the above-described ninth embodiment, the film thickness of the protective film deposited on the surface of the EUV collector mirror 3 is controlled by controlling the pressure in the second container 1b. . The pressure of the second container 1b is controlled by controlling the exhaust amount per unit time of the gas exhaust unit 12.
As described above, as a raw material containing EUV radioactive species, for example, when supplying a raw material gas containing EUV radioactive species (for example, Xe gas) and a buffer gas, the buffer gas flow rate is controlled to control the EUV collector mirror. It is possible to control the pressure in the 2nd container 1b in which 3 is installed.
This embodiment shows a procedure for controlling the pressure in the second container 1b in which the EUV collector mirror 3 is installed by controlling the flow rate of the buffer gas. FIGS. 14 and 15 show the procedure of this embodiment. A flowchart and FIG. 16 show a time chart.
Specifically, the procedure after step S111 in FIG. 12 of the ninth embodiment is changed as follows.

The control unit 30 of the EUV light source apparatus that has received the calculated deposition amount data from the film thickness measuring unit 24 in step S110 in FIG. 14 examines the magnitude of the calculated deposition amount tc and the threshold values t1 and t2 (step in FIG. 15). S111). In step S111, when t2 <tc <t1, the process proceeds to step S112. When tc ≦ t2, the process proceeds to step S213. When t1 ≦ tc, the process proceeds to step S214.
When t2 <tc <t1, the protective film on the EUV collector mirror surface does not deteriorate the EUV reflectivity of the EUV collector mirror 3, and the reflective film on the EUV collector mirror surface is caused by the EUV radiation species. It can be protected from debris. Therefore, in step S112, the control unit 31 of the exposure machine sends an EUV radiation stop signal (corresponding to an EUV radiation end signal when the exposure process is ended, or when the exposure process is paused) to the control unit 30 of the EUV light source device. It is verified whether or not (corresponding to an EUV radiation pause signal) is input.
That is, in step S112, it is verified whether an EUV radiation stop signal is input from the controller 31 of the exposure machine to the controller 30 of the EUV light source apparatus, and when the above signal is not input at the time of verification (when No). ) Proceeds to step S105.
On the other hand, when the above signal is input (when Yes), the end is reached. Note that the description of the EUV light source device stop process (stop of gas supply, stop of exhaust in the chamber, etc.) at the end will be omitted.

When tc ≦ t2, the control unit 30 of the EUV light source apparatus sends a protective film material deposition promotion command signal to the raw material supply unit shown in FIG. 3 (step S313, FIG. 16 (c)).
Receiving the protective film material generation command signal, the raw material supply unit 9 increases the flow rate of the buffer gas and increases the pressure in the second container 1b (step S315, FIG. 16 (f) (i)).
That is, the deposition rate of the protective film on the surface of the EUV collector mirror 3 is made larger than the removal rate of the protective film by debris (fast ions or neutral atoms) caused by the EUV radiation species, Promotes the deposition of protective films.
When the deposition of the EUV protective film material is promoted in step S315, the process proceeds to step S112, and it is verified whether the EUV radiation stop signal is input from the controller 31 of the exposure machine to the controller 30 of the EUV light source apparatus. If the signal is not input (No), the process proceeds to step S105.
On the other hand, when the above signal is input (when Yes), the end is reached.
When t1 ≦ tc, the control unit of the EUV light source apparatus sends a protective film material supply stop signal to the protective film material supply apparatus shown in FIG. 4 (step S314, (d) of FIG. 16).
Receiving the protective film material supply stop signal, the raw material supply unit 9 decreases the flow rate of the buffer gas and decreases the pressure in the second container (step S316, (f) (i) in FIG. 16). That is, the deposition rate of the protective film on the surface of the EUV collector mirror 3 is set to be smaller than the removal rate of the protective film due to debris (fast ions or neutral atoms) caused by the EUV radiation species.

Therefore, the protective film deposited on the reflective surface of the EUV collector mirror 3 is gradually scraped by debris (high-speed ions or neutral atoms) caused by the EUV radiation species, and the film thickness tc of the protective film eventually becomes the threshold value. Below t1, the ratio of the reflectance of the EUV light when the protective film is present on the reflecting surface to the reflectance when there is no protective film exceeds a predetermined value (for example, 80%).
When the supply of the protective film material is stopped in step S316, the process proceeds to step S112, where it is verified whether the EUV radiation stop signal is input from the control unit 31 of the exposure machine to the control unit 30 of the EUV light source apparatus. When the signal is not input (No), the process proceeds to step S105.
On the other hand, when the above signal is input (when Yes), the end is reached.
As described above, the initial state of the surface of the EUV collector mirror 3 is that the ratio between the reflectance of the EUV light when the protective film is present on the reflecting surface and the reflectance when there is no protective film is a predetermined value. This is a state in which a protective film having a thickness greater than or equal to the value is applied to the reflective film surface. Therefore, the condition of tc <t1 is satisfied at the time of the verification in the first step S111 after the EUV light source device is activated.

Here, in FIG. 3 and the like, when the insulating material 2c is made of a Si compound such as silicon nitride, for example, a discharge generated between the first and second main discharge electrodes 2a and 2b and a creeping surface generated in the preionization unit. The insulating material 2c gradually evaporates and decomposes due to the radiant heat from the discharge, and a part of it becomes vaporized Si. The vaporized Si that has reached the surface of the EUV collector mirror is deposited on the surface of the reflective film of the EUV collector mirror as a protective film.
That is, the protective film deposited on the surface of the reflective film of the EUV collector mirror 3 by performing the control procedure described in the ninth embodiment and the modified example of the ninth embodiment without providing a protective film material separately. It becomes possible to control the thickness.

(11) Tenth Embodiment This embodiment shows a control example of the EUV light source apparatus shown in the fourth embodiment (FIG. 4). FIGS. 17 and 18 are flowcharts of this embodiment, and FIG. Shows the time chart.
Here, the initial state of the surface of the EUV collector mirror 3 is a state in which a protective film having a predetermined thickness is applied in advance. The above-mentioned predetermined film thickness means that, in the EUV collector mirror 3, the ratio of the reflectance of the EUV light when the protective film is present on the reflection surface to the reflectance when there is no protective film is a predetermined value or more. The film thickness when For example, the predetermined film thickness is set so that the ratio is 80% or more.
The EUV light source device of Example 4 shown in FIG. 4 employs a structure capable of supplying a protective film material without opening the chamber 1 as described above.
Specifically, one end surface of the cylindrical protective film material 21 penetrating the insulating material 2c is opposed to the discharge portion, and the moving mechanism 25 positions the one end facing the discharge portion so as to partially protrude from the insulating member 2c. . When the protruding portion of the cylindrical protective film material 21 is vaporized and consumed due to the radiant heat generated by the discharge and it becomes difficult to supply the protective film material, one end facing the discharge portion partially protrudes again from the insulating member 2c. The positioning is performed by the moving mechanism 25.
Here, the control unit 30 of the EUV light source device has a disappearance time measuring means for measuring the disappearance time due to vaporization of the cylindrical protective film material (not shown). This disappearance time measuring means is composed of, for example, a counter.

Hereinafter, the control procedure will be described. After a standby signal is sent from the control unit 31 of the exposure machine to the control unit 30 of the EUV light source device, the control unit 30 of the EUV light source device controls the standby ionization power source unit 13 to perform standby. The steps from supplying power to the ionization unit 8, operating the preliminary ionization unit 8 to perform preliminary ionization, and sending a trigger signal to the high voltage pulse generator 14 are steps S101 to S106 in the eighth embodiment. Since it is the same, description is abbreviate | omitted.
After step S106, the control unit 30 of the EUV light source apparatus updates the count of the disappearance time measuring means that is a counter by one. That is, the count n is updated to n + 1 (step S401).
Further, the control unit 30 of the EUV light source device starts the operation of the monitor unit 23 (step S107).

The high voltage pulse generator 14 that has received the trigger signal applies pulse power between the first main discharge electrode 2a (cathode) and the second main electrode 2b (anode).
A creeping discharge is generated on the surface of the insulating material 2c, and the first main discharge electrode 2a and the second main discharge electrode 2b are substantially short-circuited. The first main discharge electrode 2a and the second main discharge electrode 2b A large pulse current flows between the main discharge electrodes 2b.
Thereafter, high-density and high-temperature plasma is generated in the high-density and high-temperature plasma generator 11 by Joule heating due to the pinch effect, and EUV light having a wavelength of 13.5 nm is emitted from this plasma. The emitted EUV light is reflected by the EUV collector mirror 3 provided on the second main discharge electrode 2b side (anode), and from the EUV light extraction unit 6 including wavelength selection means (for example, an optical filter), The light is emitted to an irradiation unit (not shown) which is an exposure machine side optical system (step S108).
After the EUV emission, a detection signal from the monitor unit 23 is sent to the film thickness measuring means 24 (step S109).
The film thickness measuring unit 24 calculates the film thickness tc of the protective film in the EUV light source device based on the received detection signal, and sends the calculation result to the control unit 30 of the EUV light source device (step S110).

Here, the control unit 30 of the EUV light source device stores in advance disappearance rate data due to vaporization of the cylindrical protective film material 21. This disappearance rate data is obtained in advance by actual measurement or calculation based on radiant heat data from the discharge part or the like.
For example, the disappearance rate is the concentration of raw material containing EUV radiation species, pressure, the amount of pulse power supplied between the first and second main discharge electrodes 2a, 2b from the high-voltage pulse generator 14, and the discharge unit. It depends on the distance from the end surface of the cylindrical protective film material 21 and the like. The product of the disappearance rate and the number of discharge pulses is proportional to the amount of disappearance of the cylindrical protective film material.
In the control unit 30 of the EUV light source device, the protruding amount of the columnar protective film material 21 protruding from the insulating material 2c with respect to the discharge unit in advance becomes a predetermined amount or less, and it becomes difficult to supply the protective film material 21. The number of discharge pulses, which is the state threshold, is stored.
That is, in step S111, the control unit 30 of the EUV light source apparatus examines the magnitude of the count number n of the disappearance time measuring means and the threshold value nm. When n <nm, the process proceeds to step S404 in FIG. When n ≧ nm, the process proceeds to step S402.

When n <nm, the protruding amount of the cylindrical protective film material 21 protruding from the insulating material 2c with respect to the discharge portion is larger than a predetermined amount. Therefore, the protective film material 21 can be supplied by heating the protective film material 21 by the radiant heat of discharge.
Therefore, when n <nm, the control unit 30 of the EUV light source apparatus proceeds to a step of examining the magnitude of the calculated deposition amount tc from the film thickness measuring unit 24 and the threshold values t1 and t2 in step S404.
Specifically, for example, the process may proceed to the procedure after step S111 of the ninth embodiment (steps S405 to S409 in FIG. 18). Therefore, the description of the procedure after step S111 is omitted.
When n ≧ nm, the protruding amount of the cylindrical protective film material 21 protruding from the insulating material 2c with respect to the discharge portion is equal to or less than the predetermined amount. Therefore, it is difficult to supply the protective film material by heating the protective film material 21 by the radiant heat of the discharge.
Therefore, in step S <b> 402, the control unit 30 of the EUV light source apparatus sends a cylindrical protective film material movement signal to the movement mechanism 25. At the same time, the count of the disappearance time measuring means as a counter is reset (FIG. 19 (o)).
The moving mechanism 25 that has received the cylindrical protective film material movement signal moves the cylindrical protective film material by a predetermined amount toward the discharge portion, and one end of the cylindrical protective film material facing the discharge portion protrudes from the insulating member by a predetermined amount. (Step S403, FIG. 19 (p)). Note that the above disappearance rate data depends on the distance between the discharge part and the end face of the cylindrical protective film material, so that the protrusion amount after movement is set to a constant value. The predetermined amount is determined at any time in consideration of the discharge state of the discharge part and the like.
After the positioning of the cylindrical protective film material is completed, the process proceeds to step S404.

(12) Eleventh Example This example shows a control example of the EUV light source apparatus shown in the fifth example (FIG. 5). FIGS. 20 and 21 are flowcharts of this example, and FIG. Shows the time chart.
Here, the initial state of the surface of the EUV collector mirror 3 is a state in which a protective film having a predetermined thickness is applied in advance. The above-mentioned predetermined film thickness means that, in the EUV collector mirror 3, the ratio of the reflectance of the EUV light when the protective film is present on the reflection surface to the reflectance when there is no protective film is a predetermined value or more. The film thickness when For example, the predetermined film thickness is set so that the ratio is 80% or more.
Hereinafter, the control procedure will be described. After the standby signal is sent from the control unit 31 of the exposure machine to the control unit 30 of the EUV light source device, the EUV light is irradiated from the EUV light extraction unit as an exposure machine side optical system (not shown). Steps until the light is emitted to the part are the same as steps S101 to S108 in the eighth embodiment, and thus description thereof is omitted.

After the EUV emission, a detection signal is sent from the monitor unit 23 to the film thickness measuring means 24 (step S109).
The film thickness measuring unit 24 calculates the film thickness tc of the protective film in the EUV light source device based on the received detection signal, and sends the calculation result to the control unit 30 of the EUV light source device (step S110). The control unit 30 of the EUV light source device stores in advance threshold values t1 and t2 of the protective film thickness. Since the film thickness thresholds t1 and t2 are the same as the film thickness thresholds t1 and t2 in the eighth embodiment, description thereof is omitted.
The control unit 30 of the EUV light source apparatus that has received the calculated deposition amount data from the film thickness measuring unit 24 in step S110 verifies the magnitude of the calculated deposition amount tc and the threshold values t1 and t2 (step S111). In step S111, when t2 <tc <t1, the process proceeds to step S112. When tc ≦ t2, the process proceeds to step S513. When t1 ≦ tc, the process proceeds to step S514.

When t2 <tc <t1, the protective film on the EUV collector mirror surface does not deteriorate the EUV reflectivity of the EUV collector mirror 3, and the reflective film on the EUV collector mirror surface is caused by the EUV radiation species. It can be protected from debris. Therefore, in step S112, the control unit 31 of the exposure machine sends an EUV radiation stop signal (corresponding to an EUV radiation end signal when the exposure process is ended, or when the exposure process is paused) to the control unit 30 of the EUV light source device. It is verified whether or not (corresponding to an EUV radiation pause signal) is input.
That is, in step S112, it is verified whether an EUV radiation stop signal is input from the controller 31 of the exposure machine to the controller 30 of the EUV light source apparatus, and when the above signal is not input at the time of verification (when No). ) Proceeds to step S105. On the other hand, when the above signal is input (when Yes), the end is reached. Note that the description of the EUV light source device stop process (stop of gas supply, stop of exhaust in the chamber, etc.) at the end will be omitted.

When tc ≦ t2, the protective film on the surface of the EUV collector mirror is too thin as a result of the protective film being scraped by debris (fast ions or neutral atoms) caused by EUV radiation species. is there. That is, it is in a state where it is difficult to protect the reflective film on the surface of the EUV collector mirror from the debris caused by the EUV radiation species, and the reflective film is damaged by the debris caused by the EUV radiation species. .
Therefore, in step S513, the control unit 30 of the EUV light source apparatus sends a protective film material supply command signal to the protective film material gas supply unit 27 shown in FIG. 5 (FIG. 22 (c)).
The protective film material gas supply unit 27 that has received the protective film material supply command signal supplies, for example, silane (SiH ₄ ) gas to the vicinity of the reflective film surface of the EUV collector mirror 3 at a predetermined flow rate (step S515, FIG. 22). (F) (g)).
The silane (SiH ₄ ) gas supplied near the reflective film surface of the EUV collector mirror 3 absorbs and decomposes light having a wavelength of 160 nm or less emitted from the plasma when EUV is generated, and as a result, the EUV collector mirror. A Si film is formed as a protective film on the surface of the reflecting surface 3.
When the supply of the protective film material is started in step S515, the process proceeds to step S112, where it is verified whether an EUV radiation stop signal is input from the exposure unit control unit to the EUV light source device control unit. When is not input (when No), the process proceeds to step S105. On the other hand, when the above signal is input (when Yes), the end is reached.

When t1 ≦ tc, the thickness of the protective film deposited on the reflective surface of the EUV collector mirror 3 by the protective film material gas supply unit 27 becomes too thick, and the EUV light is reflected when the protective film is present on the reflective surface. The ratio between the reflectance and the reflectance when there is no protective film is below a predetermined value (for example, 80%), and the EUV light intensity emitted from the EUV light source device to the exposure device is reduced.
Therefore, in step S514, the control unit 30 of the EUV light source apparatus sends a protective film material supply stop signal to the protective film material gas supply unit 27 shown in FIG. 5 (FIG. 22D).
The protective film material gas supply unit that has received the protective film material supply stop signal stops the supply of silane (SiH ₄ ) gas (step S 516, FIGS. 22 (f) and (g)).
Since the supply of the protective film material to the reflecting surface of the EUV collector mirror 3 is stopped, the protective film is gradually scraped by debris (high-speed ions or neutral atoms) caused by the EUV radiation species, and eventually the protective film The film thickness tc is less than the threshold value t1, and the ratio between the reflectance of the EUV light when the protective film is present on the reflecting surface and the reflectance when there is no protective film exceeds a predetermined value (for example, 80%).
When the supply of the protective film material gas is stopped in step S516, the process proceeds to step S112, where it is verified whether an EUV radiation stop signal is input from the control unit 31 of the exposure machine to the control unit 30 of the EUV light source device. When the signal is not input (No), the process proceeds to step S105. On the other hand, when the above signal is input (when Yes), the end is reached.

As described above, the initial state of the surface of the EUV collector mirror 3 is that the ratio between the reflectance of the EUV light when the protective film is present on the reflecting surface and the reflectance when there is no protective film is a predetermined value. This is a state in which a protective film having a thickness greater than or equal to the value is applied to the reflective film surface. Therefore, the condition of tc <t1 is satisfied at the time of the verification in the first step S111 after the EUV light source device is activated.
In the above description, the control example in the EUV light source apparatus shown in FIG. 5 has been described. However, the control method of the present embodiment can be similarly applied to the rotating electrode type EUV light source apparatus shown in FIG. it can.

It is a figure which shows the relationship between a film thickness and the transmittance | permeability of EUV light with a wavelength of 13.5 nm. It is a figure which shows the structure of the EUV light source device of the 2nd Example of this invention. It is a figure which shows the structure of the EUV light source device of the 3rd Example of this invention. It is a figure which shows the structure of the EUV light source device of the 4th Example of this invention. It is a figure which shows the structure of the EUV light source device of the 5th Example of this invention. It is a figure which shows the structure of the EUV light source device of the 6th Example of this invention. It is a figure which shows the structure of the EUV light source device of the 7th Example of this invention. It is a flowchart (1) which shows the control procedure of the 8th Example of this invention. It is a flowchart (2) which shows the control procedure of the 8th Example of this invention. It is a time chart which shows the control action of the 8th Example of this invention. It is a flowchart (1) which shows the control procedure of the 9th Example of this invention. It is a flowchart (2) which shows the control procedure of the 9th Example of this invention. It is a time chart which shows the control action of the 9th example of the present invention. It is a flowchart (1) which shows the control procedure of the modification of the 9th Example of this invention. It is a flowchart (2) which shows the control procedure of the modification of the 9th Example of this invention. It is a time chart which shows the control action of the modification of the 9th Example of this invention. It is a flowchart (1) which shows the control procedure of the 10th Example of this invention. It is a flowchart (2) which shows the control procedure of the 10th Example of this invention. It is a time chart which shows the control action of the 10th example of the present invention. It is a flowchart (1) which shows the control procedure of the 11th Example of this invention. It is a flowchart (2) which shows the control procedure of the 11th Example of this invention. It is a time chart which shows the control action of the 11th example of the present invention. It is a figure which shows schematic structure of a DPP type EUV light source device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Chamber 1a 1st container 1b 2nd container 2a 1st main discharge electrode 2b 2nd main discharge electrode 2c Insulating material 3 EUV condensing mirror 4 Debris trap 5 Gas exhaust port 6 EUV light extraction port 7 Pressure monitor 8 Preliminary ionization unit 9 Raw material supply unit 10 Raw material introduction port 11 High-density high-temperature plasma generation unit 12 Gas exhaust unit 13 Pre-ionization power supply unit 14 High voltage pulse generation unit 20 Protective film material supply device 21 Protective film material 22 Heating device 23 Monitor unit 24 Film thickness measuring means 25 Moving mechanism 26 Seal part 27 Protective film material gas supply unit 30 Control part 31 Control part of exposure machine 40 Bulkhead 41 Aperture 42 Motor 43 Laser irradiation machine

Claims (12)

A raw material supply means for supplying a raw material containing an extreme ultraviolet light emitting species and / or a compound of an extreme ultraviolet light emitting species;
Heating / excitation means for generating high-density high-temperature plasma by heating / excitation of the supplied raw material,
In an extreme ultraviolet light source device having a grazing incidence condensing optical means for condensing extreme ultraviolet light emitted from the high-density high-temperature plasma,
An extreme ultraviolet light source device, wherein a surface of the condensing optical means is provided with a Si film or a Sr film. A raw material supply means for supplying a raw material containing an extreme ultraviolet light emitting species and / or a compound of an extreme ultraviolet light emitting species;
Heating / excitation means for generating high-density high-temperature plasma by heating / excitation of the preionized raw material,
In an extreme ultraviolet light source device having a grazing incidence condensing optical means for condensing extreme ultraviolet light emitted from the high-density high-temperature plasma,
The extreme ultraviolet light source apparatus has a protective film material supply means for supplying Si or Sr to the condensing optical means. The protective film material supply means includes:
The extreme ultraviolet light source device according to claim 2, comprising: a protective film material; and heating means for heating and evaporating the protective film material. The extreme ultraviolet light source device comprises a preionization means for preionizing the raw material,
The heating means is the heating / excitation means and / or the preliminary ionization means, and the protective film material is evaporated by heat radiation from the heating / excitation means and / or the preliminary ionization means. Item 4. The extreme ultraviolet light source device according to Item 3. 5. The extreme ultraviolet light source device according to claim 3, wherein the protective film material supply means includes a material supply means for supplying a protective film material. 6. The extreme ultraviolet light source device according to claim 4, further comprising means for adjusting a gas pressure in an atmosphere of the condensing optical means. The extreme ultraviolet light source device according to claim 2, wherein the protective film material supply means is protective film material gas supply means. 8. The extreme ultraviolet light source device according to claim 2, wherein the protective film material supply means is provided on the light incident side of the condensing optical means.   A raw material supply means for supplying a raw material containing an extreme ultraviolet light emitting species and / or a compound of an extreme ultraviolet light emitting species, and a heating / exciting means for heating and exciting the supplied raw material to generate a high-density high-temperature plasma, A method for protecting condensing optical means in an extreme ultraviolet light source device having a grazing incidence type condensing optical means for condensing extreme ultraviolet light emitted from the high-density high-temperature plasma, comprising: During operation, the light collecting optical means is characterized in that Si or Sr is supplied from the protective film material supplying means to the light collecting optical means, and a Si film or Sr film is formed as a protective film on the surface of the light collecting optical means. Means protection method. Monitor the film thickness of the protective film of the condensing optical means,
10. The method for protecting a condensing optical unit according to claim 9, wherein the supply amount of the protective film material from the protective film material supply unit is controlled so that the thickness of the protective film becomes a predetermined value. Monitor the film thickness of the protective film of the condensing optical means,
The method for protecting a condensing optical device according to claim 9, wherein the pressure of the atmosphere of the condensing optical device is adjusted so that the thickness of the protective film falls within a predetermined range. The protective film material supply means is a protective film material gas supply means,
Monitor the film thickness of the protective film of the condensing optical means,
10. The method for protecting a condensing optical unit according to claim 9, wherein the amount of gas introduced from the protective film material gas supply unit is controlled so that the thickness of the protective film falls within a predetermined range.

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